| Surface:
Is it a rocky surface like Earth's, or is it a gaseous surface? |
Liquid Water:
Is it too cold or too hot for liquid water? |
Gravity:
Is there enough gravity to hold on to an atmosphere? |
Atmosphere:
Is there an atmosphere? If so, what kind of gases are in it? |
Source of Energy:
Is there energy available from sunlight or from volcanoes? |
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| Sun |
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| Mercury |
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| Venus |
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| Earth |
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| Mars |
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| Asteroid Belt |
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| Jupiter | .
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| Saturn | .
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| Uranus |
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| Neptune |
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| Pluto |
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